And there are a lot of industries out there who do QAQC via "batch testing." The bolt carrier groups of the rifles I was issued in the Marine Corps, think they pressure/magnet inspect every single one to make sure they don't accidently blow up in the face of the Marine firing the rifle? Lol... you don't get to a unit price of ~$650 per rifle that way. They'd check one BCG out of every 100 at best via "batch testing" and call all 100 BCGs good based off of testing just the 1/100. The more stringent the testing requirements are, the more expensive the unit costs are. And in *most* industries it's important to remember that your parts and equipment were made by the lowest bidder so that the guys at the top of the profit chain can maximize their gains. And the longer the parts are designed to last, the more likely that QAQC ain't going to live up to that acquisition/retention lifetime.